Signals that provide high time resolution are often used in communication systems for different purposes e.g. timing, synchronization, ranging and location awareness. Ranging or location awareness is a desirable feature in wireless networks, with applications ranging from military to safety, emergency (E911) and robotics. Research on the topic initially focused on outdoor cellular systems. These results were then extended to wireless local and personal area networks. Ranging is equivalent to estimating the time of arrival of a known signal with a narrow correlation function.
The time resolution, and therefore the precision of range estimation in any system is typically directly proportional to its actual or synthetic bandwidth. Hence, system bandwidth puts a limit on the time resolution that can be achieved by transmitting a signal on that system. Many of the designs in previous systems assume a given bandwidth and design a signal to achieve the maximum possible time resolution equal to the inverse of the total bandwidth. Recently multi-band communication systems have been proposed for ultra wideband (UWB) transmission. For example one of the leading proposals for IEEE 802.15.3a named multi-band OFDM (MB-OFDM), is a multi-band system. In multi-band systems, the whole bandwidth is divided into several sub-bands. In each time interval, a signal is transmitted over only one of the sub-bands. The system then switches to another sub-band to send another signal. Therefore, in any time interval one can send a signal with a bandwidth equal to that of a single sub-band. This would appear to decrease the achievable time resolution by a multi-band system.
In view of the above, there is a need in the art for the present invention.